Z-DNA

Z-DNA is a form of DNA in which the double helix winds to the left in a zig-zag pattern (instead of to the right, like the more common B-DNA form).

Z-DNA was discovered in 1979 by Alexander Rich and colleagues at MIT. A algorithm for predicting the propensity of DNA to flip from the B-form to the Z-form, ZHunt, was written by Dr. P. Shing Ho in 1984. This algorithm was later developed by Tracy Camp , P. Christoph Champ , Sandor Maurice , and Jeffery M. Vargason for genome-wide mapping of Z-DNA (with P. Shing Ho as the principal investigator).

Representation of various forms of DNA

Comparison Geometries of Some DNA Forms

Geometry attribute	A-form	B-form	Z-form
Helix sense	right-handed	right-handed	left-handed
Repeating unit	1 bp	1 bp	2 bp
Rotation/bp	33.6°	35.9°	60°/2
Mean bp/turn	10.7	10.0	12
Inclination of bp to axis	+19°	-1.2°	-9°
Rise/bp along axis	2.3Å	3.32Å	3.8Å
Pitch/turn of helix	24.6Å	33.2Å	45.6Å
Mean propeller twist	+18°	+16°	0°
Glycosyl angle	anti	anti	C: anti, G: syn
Sugar pucker	C3'-endo	C2'-endo	C: C2'-endo, G: C2'-exo
Diameter	26Å	20Å	18Å

References

• P. Christoph Champ, Sandor Maurice, Jeffery M. Vargason, Tracy Camp, and P. Shing Ho. Distributions of Z-DNA and nuclear factor I in human chromosome 22: a model for coupled transcriptional regulation. Nucleic Acids Research , 2004 32(22):6501-6510.